Required Sample Size

Function to determine required sample size to be within a given margin of error

nsize(b, sigma = NULL, p = 0.5, conf.level = 0.95, type = "mu")

Arguments

b	the desired bound
sigma	population standard deviation; not required if using type "pi"
p	estimate for the population proportion of successes; not required if using type "mu"
conf.level	confidence level for the problem, restricted to lie between zero and one
type	character string, one of "mu" or "pi", or just the initial letter of each, indicating the appropriate parameter; default value is "mu"

Value

Returns required sample size.

Details

Answer is based on a normal approximation when using type "pi".

Examples

nsize(b=0.015, p=0.5, conf.level=.95,type="pi")
#> 
#> The required sample size (n) to estimate the population 
#> proportion of successes with a 0.95 confidence interval 
#> so that the margin of error is no more than 0.015 is 4269 . 
#> 
#> 
    # Returns the required sample size (n) to estimate the population
    # proportion of successes with a 0.95 confidence interval
    # so that the margin of error is no more than 0.015 when the
    # estimate of the population propotion of successes is 0.5.
    # This is Example 8.25 part b. from PASWR.

nsize(b=0.02, sigma=0.1,conf.level=.95,type="mu")
#> 
#> The required sample size (n) to estimate the population 
#> mean with a 0.95 confidence interval so that the margin 
#> of error is no more than 0.02 is 97 . 
#> 
#> 
    # Returns the required sample size (n) to estimate the population
    # mean with a 0.95 confidence interval so that the margin
    # of error is no more than 0.02.  This is Example 8.4 from PASWR.